The present invention relates to the field of short-range communications, and more particularly to communications between instruments utilizing the GPIB (General Purpose Interface Bus) communication link.
At present, mainstream test equipment in a laboratory includes the General Purpose Instrument Bus (GPIB). Many automated test instruments are interconnected with each other using the GPIB communication link. Especially, some complex tasks of testing and measurement require several testing instruments comprising small testing equipment and large temperature control equipment and probe stations.
FIG. 1 is a simplified block diagram of a conventional GPIB-based testing system 100. System 100 includes a main control device (e.g., host computer) and test instruments (GPIB devices) 1 to 15 that are connected with the main control device through a GPIB interface and GPIB cable. Due to the heavy load on the GPIB interface, large interconnect parasitic capacitances, resistances, and inductances lead to the deterioration of data signal quality and error-prone transmissions. Therefore, the maximum distance for data transmission is limited to 20 m, and the maximum number of test instruments (test and measurement devices) on the same GPIB link (bus) is 15. Clearly, the limited physical interconnect distance and the number of instruments are the bottleneck of a GPIB-based testing system. Furthermore, since the GPIB interface is a wired connection, the mobility of test instruments (test and measurement devices) is relatively poor.
As the GPIB bus is mature and ubiquitous as the de-facto interconnection of programming and controlling test and measurement equipment, most testing devices have been equipped with the GPIB interface. Therefore, there is a need to overcome the limitation of the physical distance and the number of interconnected GPIB test and measurement devices.